Cursus Philosophicus Thomisticus, Secunda Pars Artis Logicae

Science can refer either to actual science or to habitual science. It was defined in the first sense above¹, when the Philosopher says that “to know is to know the cause on account of which a thing is, and that it is the cause of that thing, etc.” Habitual science is usually defined as a habit acquired through demonstration, just as, conversely, demonstration was defined² as a syllogism that produces knowing. This is not circular: demonstration is not said to be a syllogism that immediately produces the habit of science, but one that produces actual knowing—that is, scientific assent—from which the habit is generated and which inclines one to similar assent. Moreover, demonstration was not defined by that definition alone, but also by another; having thus been made known in another way, it could again be used to define science without circularity. Second, the habit of science can also be defined as “a habit that concerns a conclusion known from universal, necessary, and immediate propositions.”

To understand the account of science better, we must discern the DISTINCTION BETWEEN IT AND THE OTHER INTELLECTUAL HABITS. Here we shall treat evident habits; later, the non-evident ones. St. Thomas briefly numbers them all in the Posterior Analytics, I, final lecture.³ “We should know,” he says, “that Aristotle, in Ethics VI,”⁴ “posited five that are always directed toward truth: art, science, wisdom, prudence, and intellect. He then added two that are directed toward both truth and falsity: suspicion and opinion, to which human faith is also reduced. The first five are directed only toward truth because they imply rightness of reason. Three of them—wisdom, science, and intellect—imply rightness of cognition concerning necessary things: science concerning conclusions, intellect concerning principles, and wisdom concerning the highest causes. The others imply rightness of reason concerning contingent things.” So says St. Thomas, who treats this subject more fully in Summa Theologiae I–II, q. 57, and in his commentary on Ethics VI.

Accordingly, those five habits agree in that they are intellectual virtues, because they dispose the intellect rightly toward truth. Its disposition is right when the intellect proceeds firmly and with certainty: if it is not yet firm in truth but can lapse into falsity, it is not yet perfected in regard to truth, but is imperfect and defective. A virtue, however, is a perfect disposition. Hence there can be no intellectual virtue unless it is a certain habit concerning truth. These habits begin to differ from one another because some order the intellect toward practical truth and others toward speculative truth. Prudence and mechanical art concern what is practical; they direct contingent things—that is, art directs things to be made, and prudence things to be done. We need not treat these here.

Among the three remaining habits, which concern the speculation of necessary truth, intellect comes first: it is the principle of the others and is therefore called the habit of principles. Some have thought that it is nothing other than the intellectual power itself, which is determined by itself, without any added habit, to assent to principles—just as the will, a power, is inclined to love itself and the good in general without an added habit. See the Cursus Carmelitarum, disputation 20, q. 1, on these matters. The opposite must instead be assumed as certain, as St. Thomas assumes in Summa Theologiae I–II, q. 57, a. 3, and in his commentary on Nicomachean Ethics VI, lecture 5.⁵ There he says: “Intellect is taken not for the intellectual power itself, but for a certain habit by which a human being naturally knows indemonstrable principles by virtue of the light of the agent intellect. The name is quite fitting: principles of this kind are known immediately upon knowing their terms. Once one knows what a whole is and what a part is, one immediately knows that every whole is greater than its part. It is called intellect because it reads within by looking into the essence of a thing. Thus the cognition of principles, which become known immediately when what a thing is has been grasped, is aptly called intellect.” So says St. Thomas.

His words plainly establish the reason for distinguishing the habit of principles from the intellectual power: the power is not in itself a determinate light but is indifferent to every truth, like a blank tablet in its initial state. In becoming determinate, it depends on the light of the agent intellect, through which the intellectual power is perfected by determinate species for determinate truth. Since the habit of principles cannot make its objects or principles manifest to the intellect except in dependence on these determinate species, a light that makes the principles manifest must necessarily be added to the intellectual power. In itself, the power is not a light that manifests a determinate object, since it lacks every species from which such a light proceeds; rather, it is capable of, or receptive of, a light made determinate by the agent intellect through species. The habit of principles thus arises on the supposition that the species make things manifest, since it concerns determinate objects.

This resolves the example concerning the will that was given. The will does not receive its inclination toward the good in general or its proper good through species added to it; rather, it is inclined by itself, or is itself an inclination toward a fitting good. An inclination, by its nature, follows some form; it is not perfected by a form that represents it, as the intellect is perfected by an added form, the species of its object. If the form that the inclination follows is a proper good that naturally suits it, the inclination follows naturally, and it needs no habit to be directed toward that good. If the good is indifferent and not fitting in a fully determinate way, the will needs a habit to establish the determination appropriate to that indifference. None of this applies to the habit of principles, which belongs to the intellect on the supposition that the terms have been explained.

From this it follows that the habit of principles is not created together with the power itself, as some have said, nor is it innate by nature; rather, it is acquired through the light of the agent intellect, on the supposition of the impression of species abstracted from the senses, as St. Thomas expressly teaches in Summa Theologiae I–II, q. 53, aa. 1–2, and Summa contra Gentiles, I, chap. 78. We need not discuss it further here, since it does not belong to the logician’s task.

If you ask whether there is one habit with respect to all principles, the answer is that principles—that is, propositions lacking a middle term—can be found either in necessary matter or in probable matter. For even among probabilities there are certain first principles and immediate propositions, as we shall show below from Aristotle, Posterior Analytics I, chap. 26,⁶ and St. Thomas in the same place, lecture 44.⁷ Similarly, some principles are speculative and others practical; among speculative principles, some are most common and are called axioms, while some are particular and are called suppositions; there are also the quidditative definitions found among the subjects of the sciences.

I SAY, THEREFORE: Habits of probable principles differ from the habit of evident principles, and likewise habits of practical principles differ from speculative ones.

St. Thomas speaks of them as distinct habits in the cited question 53. The habit of practical principles is called synderesis, while that of speculative principles is called intellect. All speculative principles, however, whether axioms or suppositions, belong to the same habit.

THE REASON FOR THE FIRST PART is that probable and evident light always differ essentially. The evident and the non-evident, the necessary and the contingent, are opposed to one another; therefore they cannot be grasped by the same light. For the same reason, practical principles cannot belong to the same habit as speculative ones. Practical certainty is perfected by moral certainty, according to moral and prudential fittingness, which tends toward and applies to contingent actions that it inclines us to perform, such as acts of the will and works produced by art. For although practical principles are ultimately resolved into certain necessary truths in general, insofar as they are practical they include contingency in particular. Consider the principles “Good is to be done” and “God is to be worshipped.” In general, and in a manner of speculation, they are resolved as follows: “The account of the good itself requires, or makes it fitting, that it be done”; “worship is due to God.” In practice, however, they direct particular action by way of command or counsel: “It is fitting for you to do this good, to worship God, etc.” In this kind of direction and in making a fitting judgment, these are first principles, because they immediately show what is prudentially fitting by the terms alone. That something is prudential and fitting is necessary simply; that it practically moves and brings about an act, however, is contingent and morally certain.

THE REASON FOR THE SECOND PART is that all first principles, whether they are most common or less common, share the same formal account of assent: assent without a proving middle term, once the terms alone have been explained. The fact that the terms are more or less known to us and more or less common, and so constitute more or less common principles, pertains only to how easily and commonly the terms can be explained. Once they have been explained, it does not amount to a different mode of assent.

As for the difference between the habit of wisdom and that of science, note only what St. Thomas says in Opusculum 70, q. 2, a. 2, ad 1⁸: “Wisdom is not divided against science as one opposite against another; rather, it stands to science by way of addition. For wisdom, as the Philosopher says in Nicomachean Ethics VI, is the head of all the sciences, regulating all the others because it concerns the highest principles.” Accordingly, wisdom’s task is to judge and to resolve through ultimate causes or first principles, as St. Thomas also teaches in Summa Theologiae I–II, q. 57, a. 2, and I, q. 1, a. 6. Because the principles from which it proceeds are universal, wisdom also reflects on its own principles and those of the other sciences—not to prove them, but to explain and defend them. For this reason wisdom is said to include intellect and science, since it also extends to principles whose habit is called intellect. Wisdom is truly an inferential habit, however, using inferential proof and proceeding from principles; therefore it belongs to the order of the sciences.

To explain the subordination of sciences, three things in particular must be explained: first, what constitutes subordination; second, how the subordinating science is said to know the reason why, and the subordinated science to know that; third, how a subordinated science can have the character of science in a subject in which the subordinating science is absent, and whose principles are only believed. We will treat this third matter in the next article.

Concerning the first point, authors commonly distinguish a THREEFOLD MODE of subordination, as can be seen in the Coimbra commentators, Posterior Analytics I, chapter 10, q. 2, and Fonseca, Metaphysics IV, chapter 3, q. 2. Some sciences are subordinated by reason of an end, others by reason of principles, and others by reason of a subject. On the part of the end, this occurs when one science regards a higher end and another a lower one and is subject to it; thus architectonic arts subordinate ministerial arts to themselves: bridle-making is subordinate to horsemanship, horsemanship to military science, and military science to political science. On the part of principles, it occurs when one science receives its principles from another. This can happen because it receives principles common to other sciences, as other sciences can receive them from Metaphysics and Logic; or because it receives its own proper principles, since that science cannot resolve them by itself into principles known per se, but receives them proved and taught by another, higher science, as Music receives from Arithmetic and Perspective from Geometry. Finally, on the part of the subject, sciences are said to be subordinated when the subject of one is contained under the subject of another. As St. Thomas notes in Posterior Analytics I, lect. 25¹, this happens in two ways: either one subject is contained essentially, as a species, under the subject of another—for example, the science of human beings concerns a subject contained under animal, and the science of the heavens concerns a subject contained under mobile being—or one subject is contained accidentally under another, as Music treats of sounding number and Perspective of the visual line, where “sounding” and “visual” add accidental differences to number and line.

Of these three modes of subordination, the first is improper, because subordination there does not always provide a manifestation of truth, but only service and command. This also occurs among the virtues in the will, as temperance is commanded by charity and religion. But being subject by command is one thing, and being subordinated in science is another, because scientific subordination involves dependence in the manifestation of truth.

The second mode is proper subordination. It is found without qualification when one science has no principles except those manifested by another science, so that it cannot resolve them by itself into principles known per se. For this reason our theology is subordinated to the beatific theology, as we will say shortly. If, however, a science can resolve its principles into principles known per se but sometimes receives some principle from another science, either for proving something without qualification or for defending it, then there is subordination in a certain respect.

The third mode produces subordination in the strictest sense when the subject of the lower science adds an accidental difference to the subject of the higher science, not an essential difference or proper attribute. The reason is that the subject of the subordinated science must be foreign to or distinct from the subject of the subordinating science, just as the sciences themselves are distinct, though one depends on the other. An essential species, however, does not make a subject foreign to its generic subject, since the same science that treats a genus also treats its species; it explains its subject through division just as it does through definition. Thus Philosophy, which treats of motion, also treats of the species of motion; and Metaphysics, which treats of being, treats of substance and of determinate beings. If a proper attribute is added, this does not make a distinct science, as though one science treated the subject and another its attributes; rather, every science demonstrates some attribute of its subject. Hence, if the same science treats of a common object and its species, it will also treat of common and specific attributes. Therefore, for proper subordination on the part of the subject, one subject must add an accidental difference to another, as “sounding” adds to number and “visual” to line.

From these points we gather the CONDITIONS required for the subordination of sciences, which can be reduced to three: first, the subject of the subordinated science must contract and add something to the subject of the subordinating science; second, it must add an accidental difference that makes the subject matter of the subordinated science foreign to that of the subordinating science; third, it must add an accidental difference that in that subject matter is the principle of special attributes and knowable truths. For example, some attributes are found in the visual line that are not found in a hot or cold line; the former therefore constitutes a distinct subordinated science, but the latter does not.

To explain this matter more fully, YOU WILL OBJECT: First, theology is subordinated to the beatific science, as St. Thomas teaches in Summa theologiae I, q. 1, art. 2, and yet both sciences treat of the same subject, namely, God. Therefore the subordination of sciences does not require the subjects to be distinct through the addition of an accidental difference.

Second, if the subordinated science has as its subject something contracted by an accidental difference, it follows that it has an accidental being as its object. The visual line and sounding number, for example, are accidental beings. But there is no per se science of accidental being.

Third: Either that accidental difference is accidental to the object in the being of the thing or in the being of what is knowable. If in the being of the thing, this contributes nothing to subordination: many sciences treat of a subject determined by an accidental difference and yet are not subordinated to a higher science. Philosophy treats of mobile being but is not subordinated to a science of being; Medicine treats of a healthful body but is not subordinated to Philosophy, which treats of body. Likewise, there would be no reason why the visual line or sounding number, for example, should constitute a subject of subordination, while a line or number with another accident, such as a colored or hot line, a visible number, or something similar, should not. If the difference is in the being of what is knowable, it follows that the subordinating and subordinated sciences differ only accidentally, since they differ by an accidental difference in the being of what is knowable; yet Music and Arithmetic differ essentially.

Finally, Metaphysics proves the principles of all the sciences and thereby subordinates the others. Yet the other sciences do not add an accidental difference to its subject, since nothing adds an accidental difference to being, which is transcendental. Therefore, and so on.

To the first, the reply is that our theology is not subordinated to the beatific science on the part of the subject, as though a foreign and distinct subject were subordinated to the subject of a higher science, but on the part of principles and evidence: theology receives from the beatific or divine science evidence for the principles that it now believes by faith. This suffices for true and proper subordination, insofar as the evidence of one science's principles depends on another. Our theology does not, however, have all the conditions required for subordination on the part of the subject, because in fact it does not have a subject different from the beatific science's subject. Thus on the part of the subject there is no subordination but identity: it does not add an accidental difference to the subordinating science's subject but regards the same subject under a different formal aspect, namely, as virtually revealed, whereas the beatific science regards it as clearly seen. See Cajetan, Summa theologiae I, q. 1, art. 2.

To the second: Authors hold various opinions about the subject of a subordinated science. Some think that there can be science of accidental being, provided it is not accidental being by chance or fortune. See the Coimbra commentators, Posterior Analytics I, chapter 10, q. 2, art. 1. This reduces to what others say: the object of the subordinated science is one accidentally in the being of the thing but per se in the being of what is knowable. This clearly admits that there can be science of accidental being. But it conflicts with the very character of accidental being, because such a being does not consist of one genus and difference, and consequently does not have one definition. Since a definition is a principle of science, the unity of science depends on the unity of that definition, as we will say in the next question; we said more about this above, qq. 5 and 7.

The reply, then, is that the subordinated science does not have as its subject that aggregate considered as accidental being, constituted from an accidental difference and the subject of a higher science. Rather, it regards one of those things per se, though not absolutely, but as modified and connoted by the other. For example, Perspective treats of the visual insofar as it is modified by and connotes line. It is therefore no problem that a subject should be per se knowable and ground necessary truths, even though to ground them it requires something accidental as a connoted and oblique feature. For many properties or proportions do not belong to a thing absolutely, but on the supposition of some state or condition that is accidental to it yet required per se for the property to follow. Rest, for example, does not follow a stone absolutely, but insofar as it is at the center. Similarly, some properties or proportions follow the visual or the sounding, not absolutely, but the visual as it is in a line and the sounding as it is in number. Thus they do not belong to something constituted and aggregated accidentally, but to one thing per se with the connotation of another.

To the third, the reply is that the subordinated science adds an accidental difference to its subject on the part of the thing itself, but in such a way that this is a required condition for a per se truth to result, one that is truly knowable through dependence on the subject of the higher science. The stated conditions must therefore all be present for subordination: the accidental difference must help constitute different proportions or connections of truth, and these necessary truths or connections must then depend, for their manifestation, on the principles of the higher science's subject. Thus the proportions of the visual line depend per se on the principles of line, and those of sounding number on the principles of number. The truths of mobile being, however, do not depend on the principles of being as such; the science of mobile being resolves itself into per se known principles of its own genus, rather than proving them by resolution into principles of another science, as subordination requires. If a line or number is given a difference that does not constitute a special per se demonstrable truth, such as the line's being hot or cold, or if the manifestation of those truths does not depend on the subject of the higher science, this cannot constitute subordination.

To the fourth, the reply is that Metaphysics is the highest science because its object is higher and more universal than those of the other sciences, and it proceeds from first principles. The other sciences do not, however, receive the manifestation and proof of their principles from it, because they have principles known from their terms, into which they resolve per se. Any science that resolves itself per se into principles known per se is not subordinated; for subordination, it must have principles manifested and proved by another science. Metaphysics does explain and defend the principles of the other sciences by reducing them to impossibility, but it does not prove and demonstrate them a priori. And if the other sciences sometimes proceed in their demonstrations from principles of Metaphysics, just as they sometimes proceed from principles of Logic, as we said in q. 1, art. 5, this does not mean that they are subordinated to those sciences without qualification. It is not total dependence on another science for the evidence of one's principles, such that one has no principles known per se into which to resolve them; rather, it is being helped in some proof by principles of another science as an external and transferred proof. This is subordination in a certain respect.

Concerning the SECOND POINT, namely, how to understand the Philosopher's statement that “it belongs to the subordinating science to know the reason why, but to the subordinated science to know that”: setting aside the various explanations that can be seen in Master Soto, on this first book, q. 5, ad 6, and the Coimbra commentators on chapter 10 of this book, q. 2, art. 3, we say first that the Philosopher did not state absolutely that a subordinated science knows that, as if every subordinated science knew that—or, worse, as some understand it, that the subordinating science reaches the subordinated science's conclusions in its own determinate subject matter, whereas the subordinated science reaches them from effects and by demonstration of the fact. Rather, the Philosopher said that it is proper to the sciences of sensible things—that is, those that descend to sensible matter—to know that, whereas it belongs to mathematicians to know the reason why. That is, among the sciences subordinated to Mathematics, those that extend to sensible things know by the science of the fact, because they reach sensible things by induction and descend to experience. If they wish to know the reason why for the very same things they know by experience, they must use principles taught by Mathematics, or by the subordinating science. For example, a surgeon says that circular wounds heal more slowly, first from long experience and second from the circular figure itself. But if the surgeon wishes to give the cause and explanation, he must turn to Geometry, which says that a circular figure joins its parts with greater difficulty because it lacks angles. Thus we are not compelled to verify Aristotle's proposition in every subordinated science, but only in one that descends to sensible things. Such a science can reach sensible things in singulars and use induction from them, which is to know by the science of the fact. To know the reason why, however, it must borrow principles from a higher science and apply them to the sensible matter it treats. Therefore, a subordinated science is not said to know that with respect to the subordinating science's principles that it uses, but with respect to the conclusions it can know from those principles applied to its own matter and also reach through experience itself. It knows them by the science of the fact not precisely insofar as it is subordinated, but insofar as it is sensible and descends to sensible effects.

FROM THIS YOU WILL GATHER TWO POINTS: First, when the subordinating science is said to know the reason why, this does not mean that it knows the subordinated science's conclusions themselves and descends to demonstrate them. That cannot hold unless the subordinating science changes its abstraction and descends to the matter of another science, which would change the species of that science, derived as it is from abstraction and a different immateriality. Thus, as Cajetan aptly notes in Posterior Analytics I, chapter 12, the subordinating science is said to know the reason why in isolation and in general, not as applied to this particular matter: it teaches principles only in general, which are later applied by the subordinated science to its determinate matter. Geometry does not demonstrate that circular wounds heal more slowly; the geometer treats nothing about wounds, but only teaches in general that a circular figure, because it lacks angles, joins together with greater difficulty, which he demonstrates abstractly. The surgeon takes this principle and applies it to his own subject matter, showing that circular wounds join more slowly.

Second, when the subordinated science is said to know that, this should not be understood privatively, as if it demonstrated only the fact and in no way the reason why. By taking principles from the subordinating science it truly demonstrates the reason why; indeed, the chief point of subordination is that, taking principles from a higher science, it demonstrates its own conclusions. But because it does not have those principles from itself or resolve them from itself into principles known per se, but receives them as made known by another, higher science, the higher science is credited with knowing the reason why: its principles are taken and applied to the matter of the lower science so that the lower science's own conclusions may be demonstrated through their reasons. Those conclusions are also known further through experience itself, and thus that science is said to know them by the science of the fact through its own resources, that is, through experience and effects.

THE REASON FOR DOUBT is taken from this: science that does not resolve as far as principles known per se, or cannot prove them through another science, merely believes those principles; therefore it does not in fact share in evidence and certainty, and so in fact is not science.

The consequence is clear, because evidence is obtained through demonstration or resolution into principles known per se. Therefore, if an inferior science stops at a proposition it cannot further prove because it is not continued into a superior science, nor does it resolve by itself into principles known per se, it lacks evidence and consequently cannot derive evidence for its other conclusions, since it lacks evidence for its principles.

This is confirmed because in any science, if someone forgets the middle term by which a conclusion is proved, science is destroyed in him, since he has neither evidence nor proof. And if, per impossibile, someone lost the habit of principles, science could not remain because the principles would no longer remain. Similarly, then, one who does not possess the subalternating science, from which principles are supplied to a subalternated science, cannot have the true nature of subalternated science, because he lacks evidence for the principles and the middle term. The authority of St Thomas, De veritate, q. 14, a. 9¹, also supports this: “Whatever is known properly by science is known through reduction to first principles, which are immediately available to the intellect.” Therefore one who does not know by reduction to first principles—as a subalternated science does when it is not continued into the subalternating science—will not properly have science. Likewise, in Sentences III, d. 33, q. 1, a. 2, quaestiunc. 4², he says that “if there were some science that could not be reduced to principles naturally known, it would not be of the same species as another science.” But a subalternated science without continuation to the subalternating science cannot be reduced to principles known per se. Therefore when it is not thus continued, it does not have the nature of science.

NEVERTHELESS, WE MUST SAY that the subalternated science is the same specific habit whether it is continued into the subalternating science or not; yet, on the part of the subject, it has the imperfect state of science for as long as, in fact, it cannot resolve into principles known per se through the subalternating science.

This conclusion is common among Thomists. See Cajetan, Summa theologiae I, q. 1, a. 2; Master Soto, book I of the Posterior Analytics, q. 5; Sanchez, book VII, q. 2; Araujo, Metaphysics I, q. 4, a. 1; and the Carmelite Course here, disp. 19, q. 3. It is taken from St Thomas, Summa theologiae I, q. 1, a. 2, where he unqualifiedly calls that which is subalternated a science. In De veritate, q. 14, a. 9, ad 3³, he grants that “one who has subalternated science does not perfectly attain the nature of knowing unless his cognition is in some way continued with the cognition of the one who has the subalternating science. Nevertheless, the inferior knower is not said to have science of what he presupposes, but of the conclusions that necessarily follow from the principles presupposed.” See also more fully Opusc. 70, q. 2, a. 2, ad 5, 6, and 7⁴, and To Hannibald, I, d. 1, q. 1, a. 1⁵, where he teaches that “the proximate principle of the first sciences is the intellect; for those sciences that presuppose their principles from others, the proximate principle is belief in the principles presupposed from others, while their first principle is the intellect. The certainty of these sciences is perfected, however, when by resolution they reach the intellect of the first principles themselves.”

The reason for the conclusion is that the habit of subalternated science, even when it is not continued into the subalternating science, by its very nature demands and inclines toward being continued with it. Therefore in itself it is a scientific habit, insofar as it has an inclination to full evidence through continuation with the superior science.

The consequence is clear: if the habit itself demands continuation with the subalternating science, then when it is actually continued, it is not destroyed but perfected, nor is another habit generated; rather that very habit is continued with the superior. Otherwise it would seek that continuation in vain, if it could not itself be continued with the subalternating science and, when continuation occurred, a new habit of a distinct species—scientific, whereas it had not been scientific before—were generated. Thus there would never be a subalternated habit that demanded continuation with the subalternating science. But if it is the same habit that is continued and discontinued from it, then even when it is not actually continued, it is science by its inclination and root.

The antecedent is proved as follows: one who acquires the habit of a subalternated science separately from the subalternating science proceeds from principles manifested in the subalternating science, and thus presupposed to be evident. Therefore by its nature that habit inclines and calls for continuation with the manifestation of the subalternating science. Otherwise it would not by itself proceed from principles manifested by that science if it did not intrinsically incline toward those principles precisely as manifested by the superior science. If they are in fact manifested to it, this is most in keeping with its nature; it therefore has an inclination toward evidence, although on the subject’s side it does not make that evidence explicit, owing to the lack of continuation with the superior science. A habit could not incline toward such evident principles if it were not science, since a habit intrinsically lacking evidence cannot incline toward evidence or seek it.

As Cajetan rightly observes in the cited place, subalternated science may be said not to be science because it lacks the perfect nature of science, that is, its state; nor is it an intellectual virtue as to its state. It is one as to inclination and substance. Just as a virtue remains in the substance of virtue in a sinner, although by nature it seeks continuation with the ultimate good end and does not then have that continuation, so when a science or habit has an inclination toward evidence and can be perfected through it, it has the nature of science as to substance: by its inclination and root it seeks evidence for the principles, even though an impediment on the subject’s side prevents it from possessing that evidence. A sign is that the faith by which one believes these principles to be evident in a superior science is not the reason for inferring conclusions in the inferior science by virtue of belief or fallible authority, but because those conclusions presuppose evidence in the superior science. Theology excels in this respect: it relies on infallible faith, and thus finds principles actually certain in faith itself, not merely presupposed and radical, though not evident, for evidence is presupposed in the superior science.

If you ask how subalternated science can be certain and evident as to substance and yet not give the subject that denomination, the answer is that it gives the denomination of science radically and as to substance, but not as to state, because the subject is impeded by lacking continuation with the superior science. Conversely, faith or opinion can lose extrinsic fear, that is, actual and denominative hesitation of the intellect, as will be said in the next article, while remaining intrinsically fallible in itself.

TO THE OPPOSING ARGUMENT it is answered that science which does not resolve into first principles either radically, by its inclination, or actually, according to its state, has no true nature of science, but rests on belief in the authority of another. If, however, it has radically and by inclination the demand to resolve into first principles, even though in fact it does not resolve because continuation with the subalternating science is lacking, it is nevertheless science. Per se it does not rest on belief; belief merely supplies the place of the superior science. By its very nature it seeks resolution into the superior science, continuation with its evidence, and perfection there.

As to the proof, evidence is obtained through proofs and resolution into principles according to each science’s mode. Sometimes evidence is only radical, according to an inclination toward continuation with the superior science; sometimes it is actual and perfect, through proofs actually resolved and continued into the superior science. Therefore a failure of proof that is only on the side of the knowing subject, not on the side of the science itself and its inclination, does not remove the nature of science essentially and intrinsically, but only as to its state.

To the confirmation, if someone forgets the middle term in such a way that it remains neither in himself nor in another thing into which he by nature seeks and inclines to be continued, he absolutely loses the science, because he retains neither the premises nor their proof. But if he retains the premises or the proving middle term of the conclusion, while presupposing the proof as evident in another, superior science and intrinsically inclining to possess it, then science is lacking only as to its state, not as to the intrinsic nature and inclination of the scientific habit that seeks such evidence. Likewise, if someone lost the habit of first principles but retained propositions knowable through that habit, while not knowing the explanation of the terms and so not knowing those propositions as self-evident to him, he would truly possess science, because he would proceed from propositions self-evident absolutely and in themselves, although accidentally, for lack of that explanation, he would lack actual, term-based evident knowledge. This does not happen so easily, however, because the propositions of first principles immediately become self-evident.

As to the passages of St Thomas, he denies only that subalternated science is perfect science, not that it is absolutely science on the side of its intrinsic inclination, since in the places cited above he absolutely calls it science, in the sense that it is intrinsically distinct from a habit lacking evidence, in which no inclination toward evidence for principles remains. He speaks in this sense in Sentences III when he says that what cannot be reduced to first principles is not science. The phrase “cannot” means cannot by inclination and root, rather than cannot by actual evidence. For what in no way can have evidence is only a habit without evidence, such as faith and opinion, and so it is not science univocally. Subalternated science is said to be perfected in the vision of the thing because it does not have the perfect state of science without that vision; yet its ability to be perfected by it is a sign that it is intrinsically and substantially science, since a habit lacking evidence cannot be perfected in the vision of the thing.

From these points it is inferred that the Thomists rightly defend the claim that the Theology possessed in this life remains in the homeland and becomes evident there, because by its inclination and intrinsic root it seeks evidence and continuation with the subalternating science, which is beatific science; while on the way, accidentally, it uses faith as supplying and presupposing principles that are evidently known in the superior science.

Habits of non-evident cognition are reduced to three: opinion, faith, and suspicion.

OPINION IS DEFINED as assent to something on account of a probable reason and motive, accompanied by fear of the opposite side. Created faith (for we are speaking only of this) is a thought with assent, or the assent of one who thinks, on account of the authority of the speaker. Suspicion is assent inclining toward one side on the basis of some slight sign. Finally, doubt is cognition without firm assent, that is, without a determinate inclination toward either side. Thus teaches St. Thomas, II-II, q. 2, a. 1, and q. 14 of the De veritate, a. 1.¹

From these definitions it is easy to understand what the habits of these non-evident cognitions are, by putting “habit inclining to assent” in place of the term “assent.” Doubt, however, does not seem to generate a habit, because one who doubts has no assent but suspends judgment, and therefore does not generate a habit that inclines determinately, but rather one that suspends itself from inclination. Yet no habit seems necessary simply for suspending, since this is a negation, unless something positive is joined to it: namely, that it be done for some end, for example, to avoid effort or for the good of virtue, and so on. That concerns something moral pertaining more to the will than to the intellect.

THREE THINGS HERE NEED EXPLANATION: First, what uncertainty and non-evidence consist in; this must be explained from their opposites, evidence and certainty. Second, whether uncertainty and non-evidence are so intrinsic to these habits that they can in no way be separated from them. Third, whether these habits differ essentially from one another.

On the first: Certainty, as may be gathered from St. Thomas, III, dist. 23, q. 2, a. 2, question 3², is nothing other than the determination or adherence of the intellect to one thing. Certainty is therefore greater in proportion to the strength of what causes this determination. Two kinds of certainty are suggested: one caused, or formal, on the side of the act; the other causing, on the side of the object or subject. For sometimes certainty is caused by the known object, which suffices to determine the intellect; sometimes by the will, which stands on the side of the subject because the object by itself does not suffice to determine it. Thus St. Thomas adds there that certainty is caused in the intellect of principles because something can be sufficiently inspected through the principles themselves; in science, because it is resolved into principles seen in themselves; but in faith, because the will commands the intellect. There is thus a threefold certainty: formal, in the act; objective, on the side of the object that compels assent; and subjective, on the side of the will that adheres and makes the intellect adhere. Hence, when God moves someone to faith, he first touches the will and through it the intellect, so that the intellect is determined through the will’s choice, as St. Thomas explains in his commentary on Hebrews, ch. 11, lect. 1.³ This subjective certainty is without evidence, for the will supplies what is lacking to the object on the side of evidence. Objective certainty, however, is necessarily joined to evidence, because it arises from an object that is sufficient to move by itself, which does not happen without evidence.

Evidence, as may be gathered from St. Thomas, II-II, q. 1, a. 4, is that which moves a power by itself; for those things are said to be seen which move the intellect or sense by themselves. He gives three modes of vision or evidence in III, dist. 24, q. 1, a. 2, question 1.⁴ First, the notion of vision is found in simple cognition, because vision is found primarily in sense, “insofar as the visible species is actually formed in sight.” Transferring the term “vision” to the intellect, we properly say that we see intellectually when, through intellectual light, the intellectual form itself is made present in our intellect, whether through natural light, as when we understand the quiddity of a human being, or through supernatural light. Further, those complex objects whose cognition arises from the vision just described are said to be seen by the intellect: thus by natural light we see first principles, which we know as soon as their terms are explained. Further still, those things that we can resolve into these principles are said to be seen by reason, as are things we know to have been proved demonstratively.” Behold all the grades and modes of vision taught by St. Thomas. He attributes vision not only to things seen immediately and intuitively in themselves, but also to things resolved by science and demonstration into what is known in itself. For precisely because they are connected by necessary connection to things seen in themselves, they remain illuminated by those principles, as if they had been seen. Evidence is also recognized by its effect, when something is presented to the intellect in such a way that it fully compels it, so that the intellect is at rest and does not need to be moved by anything extrinsic, namely by the will supplying the object’s insufficiency. For if the intellect is fully moved by the object, it reaches the object as it is in itself; otherwise it would not be said to be moved precisely by the object’s power, if the object did not actualize the power entirely but were reached only imperfectly. In that case it would not overcome the power’s resistance or compel it.

It remains explained, then, what non-evidence and uncertainty are: they are privations of evidence and certainty. An object presented with such a privation is not sufficient to compel and move a power entirely. Since it does not determine the power fully, it needs an affection of the will inclining the intellect, as appears in faith. The will does not do this by adding light to the intellect so as to supply the motion of an obscure object. For then that addition of light would either make the object evident or leave it obscure. If it made it evident, faith would be removed through the will; if it remained obscure, it would remain as before, and the obscure light would not be supplied by adding light. Rather, the will is understood to incline the intellect insofar as the will’s own affection and adherence to the object as something fitting is represented to it. Therefore the intellect adheres to the object itself, not because the truth is more manifest, but because it is fitting to the will, provided the intellect is not certain that the object is false. Once that disposition and affection of the will are removed, the object remains as probable or doubtful. This is why faith requires the command of the will not only for the execution of the act in its exercise, but also for its specification, that is, for determination on the object’s side: by presenting the object’s fittingness, the will supplies what the object cannot determine through the evidence of truth.

On the second question, whether opinion essentially has uncertainty and fear attached to it, there is difficulty because of certain propositions that we believe without any doubt, for example, that Rome exists, though we have not seen it. Likewise, within the domain of what is opined there are certain immediate propositions, as it were principles, since they are not proved by other probable propositions. An example is “Every mother loves her child,” as Aristotle expressed it in Posterior Analytics I, ch. 26⁵, and St. Thomas there, lect. 44.⁶ The reason is clear: even in probable arguments there is no infinite regress, so we must stop at some proposition that lacks a probative middle term. This cannot be necessary but must be probable, because a contingent conclusion does not follow validly from a necessary premise. Therefore those first propositions are both immediate and not necessary, but probable. Hence in these and similar cases THERE IS A DIFFICULTY about how uncertainty and fear can be separated from them.

Some, then, distinguish two kinds of uncertainty or fear: one on the side of the middle term or formal reason for knowing, the other on the side of the effect it leaves in the subject, namely the subject’s actual adherence to the thing. They say that the first cannot be separated, but the second can, as experience itself shows when we believe many things we have not seen without any hesitation.

Yet a difficult argument remains to be solved: how can someone form a judgment that is intrinsically non-evident and uncertain, while the subject does not share that uncertainty, when the subject tends toward the object only through that uncertain act? The authors of that solution reply that the intellect shares the intrinsic fear that belongs to the object’s side, but lacks only the fear that comes from the will, because the will adheres so firmly to one side that it does not allow the opposite side to be feared or doubted. For in these obscure assents the will’s motion always has a place. Hence, if the will is wholly firm, every doubt is removed.

However, because the will sometimes becomes wholly firm in an object, as is clear in divine faith, while the intellect still undergoes speculative doubt and fluctuation, as happens to those tempted concerning the faith without obstinacy—although the intellect does not suffer such doubt regarding certain propositions of human faith, for example, that Rome exists—IT MUST BE SAID FURTHER that in faith and opinion there can be moral evidence and certainty, not concerning the truth they reach, for this always remains obscure and uncertain; this is called intrinsic or metaphysical uncertainty because it concerns the truth itself. Rather, this evidence and certainty concern credibility or probability. When so many motives are accumulated that they make credibility evident, leaving no room for disbelief, then all extrinsic fear is removed, since the motives and inducements to faith are called extrinsic to the assent of believing. But as regards the very truth believed or opined, so long as it is not seen in itself, the intellect always remains intrinsically without evidence and unsatisfied. Thus, although it can be free from all moral fear or movement of doubt, it cannot be free from fear concerning the manifestation and evidence of the truth. The fear of obscurity can therefore never be removed from faith and opinion, and consequently neither can the fear of objective uncertainty in things reached by human faith or opinion. In divine faith, objective uncertainty does not occur because of the infallibility of the testimony; intrinsic imperfection of obscurity nevertheless remains. Whatever wavering or doubt there may be in believing or opining is removed or diminished to the extent that the motives and reasons inducing credibility or probability increase; they can increase in evidence to the point of excluding all such fear. A sign of this is that even temptations concerning the divine faith are usually diminished by accumulating motives that induce faith, and those fully convinced by signs to believe do so without a movement of speculative doubt.

If you object that science can never cast off certainty, so neither can opinion or faith cast off fear, since science stands to certainty as opinion stands to fear, the consequence is denied. In science there is only one certainty, namely insofar as it reaches the thing in itself. In opinion, however, there is a twofold fear: one intrinsic, with respect to the truth; the other extrinsic, with respect to the motives inducing probability or credibility. Thus one can be removed while the other remains.

On the third difficulty, concerning the formal distinction among these habits of non-evident cognition, I say briefly that human faith and opinion differ essentially, because their means are entirely different and the formal reason for knowing differs greatly in each. Opinion uses reasons that produce probability and have a connection that, though not complete, is probable and plausible; on this account the intellect can be inclined, though not moved and compelled entirely. Faith, by contrast, relies only on the authority of the speaker and thus does not use proof or reasoning. Once the authority is known to be worthy of faith, and the proposition itself does not appear impossible or false, this alone suffices for assent in believing. Therefore they differ essentially in the mode and formal reason by which they tend toward their objects.

On this conclusion one may consult St. Thomas, II-II, q. 2, a. 1, and more fully in III, dist. 23, q. 2, a. 2, question 1⁷, where he sets out the difference between the intellect’s operation through the habit of principles, through science, through faith, and through opinion. He shows that “thinking with assent” distinguishes the believer from all the others, understanding “thinking” not as an act of the imaginative power but as an act or movement of discursive reason, and “assent” as a determinate judgment. One who understands through the intellect of principles has assent without thinking, that is, without a movement of reasoning, but only through the explanation of terms. A knower has cognition and assent because, by thinking or reasoning, he reaches assent through the vision of principles, where the intellect’s movement terminates; hence he includes vision insofar as he is ordered to principles that are seen in themselves. A believer has assent with thinking because he does not reach assent through thinking and reasoning, nor is he led to principles known in themselves; rather, he is determined to assent from some extrinsic principle, namely the will’s choice, because it appears good to him. In this he has firmness and assent, yet he undergoes movement or thought even concerning the opposite. One who opines has thinking without perfect assent, though he has some assent insofar as he adheres to one side more than the other on the strength of some proof that is not evident but merely apparent. Thus, because he accepts one side while fearing the other, his assent is not fully determined. One who doubts has no assent at all, but only thought, suspending judgment. One who does not know has neither assent nor thought. Thus St. Thomas. It is therefore clear that opinion differs in species from faith, both by reason of the means by which it is moved—faith on account of the speaker’s authority, opinion through the probability of reasons—and by the mode of its being moved: faith assents through the choice of the will, while opinion assents with fear arising from the reasons.

If you ask ABOUT SUSPICION, whether it differs essentially from opinion and faith, the answer is that it belongs to opinion as something imperfect within that genus. Hence St. Thomas, in the cited passage from the Sentences, did not list it separately, but explained it in the cited place from II-II, saying that suspicion and opinion differ because one who suspects inclines on the basis of some slight sign, whereas one who opines adheres to one side, though with fear of the other; thus they differ only by more and less in adherence. Or one may say that suspicion is something common, as an imperfect state in either genus. For if the slight judgment that moves someone is a statement of little authority, it is reduced to weak faith, by which someone believes readily. But if the slight judgment is a reason with little weight, it belongs to imperfect opinion.

BUT YOU WILL OBJECT: Faith and opinion seem to agree essentially. Each requires probable reasons, for no one is moved prudently to believe unless something is presented to him as probable or plausible. Each also requires a pious affection, because opinion too is not moved to assent by the force of an object that compels; consequently, it must be determined by something extrinsic, that is, by the will supplying the object’s determination. Therefore opinion and faith agree in their formal motive, differing only on the side of the different matter, as two opinions can differ.

Second, opinion is no less uncertain and non-evident than faith. Therefore the motive of each agrees essentially in its formal reason for moving. Hence the Philosopher says in Topics I, ch. 7⁸ that faith is an opinion established by induction or probable syllogism.

To the first, the answer is that faith does not formally require probable reasons, but presupposes them and requires them antecedently; opinion, however, requires them essentially and formally, while the movement of the will is joined to it accidentally. For in faith, the probability of reasons is required for two things: first, so that the matter does not appear impossible; second, so that it or the speaker’s authority appear fitting, and so that the will be affected by them. Once this affection is present, the intellect is moved to believe through the presentation of what is good and fitting. On this St. Thomas grounds the claim that the pious affection preceding divine faith arises from the intellect’s presentation of the fittingness of the promised good, in De veritate, q. 14, a. 2, ad 10.⁹ Hence, since the intellect’s presentation of the good’s fittingness is ordered only to attracting the will, although it requires a supernatural presentation if the good proposed is supernatural, it does not require evidence concerning the truth of what is presented, but evidence concerning the good’s fittingness. This is to be practically, not speculatively, evident; it does not require supernatural evident light, but a prudential judgment from special supernatural help. In opinion, by contrast, the probability of reasons is required not to present a good but to make the truth manifest, though not fully and perfectly. Thus opinion’s adherence, which is neither full nor firm, does not essentially depend on the will, but can be found without it, resting only on the weight and force of the reasons. If a movement of the will is joined to it, this is not something required first and essentially, but accidentally, because the will sometimes uses opinion as faith, as when a judgment is produced more by passion than by the probability and weight of reasons alone.

To the second, the answer is that faith and opinion agree in being uncertain and non-evident in a generic sense, but differ in species because their means and modes of moving differ, as was said. The Philosopher, however, takes faith broadly, as in common speech whatever is not seen is called faith or opinion.

THREE COMPARISONS can be made between opinion and science. The first compares act with act, namely, certain and evident assent, which is science, with uncertain and nonevident assent, which belongs to opinion or faith. The second compares habit with habit: the habit of science is an inclination to evident assent, contrary to the inclination that inclines toward nonevident assent. The third is between habit and act, as when someone has the habit of opinion and elicits an act of science, or the reverse.

As for the first comparison, some absolutely judge that an act of science and an act of opinion can coexist in the same intellect concerning the same object, because they think they are merely disparate, not privatively opposed as evident and obscure, insofar as they proceed from different motives. So Master Cabero here, tractate 7, disputation 4, doubt 6. Others think that opinion, which is joined to actual hesitation and fear, cannot coexist with an act of science, but that it can if it lays aside that fear in the manner explained in the preceding article. So the Conimbricenses, Posterior Analytics, book 1, ch. 26, q. 2, a. 2. They also hold, in a. 3, ad 4, that divine faith, which has certainty, does not conflict with science; thus they seem to posit no opposition between evidence and nonevidence once uncertainty is removed. Finally, some recent authors, commenting on St. Thomas, Summa theologiae, II-II, q. 1, aa. 4 and 5, distinguish abstractive evidence from intuitive evidence, which is vision. They say that vision is wholly incompatible with faith or opinion because it reaches the thing immediately in itself, but that abstractive evidence is not incompatible, because it does not immediately reach the thing itself and thus does not directly conflict with the obscurity of faith.

NEVERTHELESS, I SAY FIRST: An obscure and an evident act, whether of opinion or faith, and whether of intuitive or abstractive evidence, are opposed to one another in the same intellect by privation on the side of the subject; the same holds for a certain and an uncertain act.

Many authors agree with this conclusion; you can consult them in the Carmelite Course, disputation 20 of Logic, question 4. It is also the express position of St. Thomas. For in On Truth, q. 14, a. 9, ad 6,¹ he says “that it does not seem possible for someone to have both science and opinion of the same thing, because opinion involves fear of the opposite part, and science excludes this fear.” And in Posterior Analytics, lecture 44,² he says: “It is manifest that the same thing cannot be wholly known and opined at the same time, because a person would at once judge that it could be otherwise and that it could not be otherwise.” This agrees with what he resolves in Summa theologiae, II-II, q. 1, a. 5, ad 4, where he teaches “that in one person science cannot coexist with opinion or faith at the same time concerning the same thing in the same respect, though for different reasons. Science and opinion cannot coexist simply concerning the same thing, because it belongs to the nature of science that what is known be judged unable to be otherwise, whereas it belongs to the nature of opinion that what is opined be judged able to be otherwise.” Of faith and science he adds “that they conflict only on the side of what is seen and what is not seen.”

It is no objection that St. Thomas, in Summa theologiae, I-II, q. 67, a. 3, teaches absolutely that nothing prevents perfect and imperfect cognition, on the side of the medium, from applying to one object in one subject: one person can know the same conclusion through both a probable and a demonstrative medium. Therefore, he plainly judges that an act of opinion and an act of science can coexist in the same subject, since they proceed through different media; for a probable medium and an opinion-forming medium are the same. He teaches something similar in 3 Sent., d. 31, q. 2, a. 1, question 1, ad 4³, and Summa theologiae, III, q. 9, a. 3, ad 2. These passages, I say, are no objection, although the cited texts seem difficult in particular, so that Father Suarez, in his commentary on that question 9 of the third part, wanted St. Thomas to have held that opinion and science can coexist. Yet the solution is derived from this very passage, where St. Thomas says “that opinion caused by a dialectical syllogism is a way to science, which is acquired through demonstration; once science has been acquired, however, cognition acquired through a dialectical syllogism can remain, as it were, consequent upon demonstrative science, which is through a cause.” Cajetan astutely weighs this passage: St. Thomas's words must be distinguished, for he first names a dialectical syllogism as opinion, and in the second place does not call it opinion but cognition. This shows that opinion is not simply the same as probable cognition taken in any way whatever, but rather as it is exercised as a reason and motive for assent with fear of the opposite part. But when St. Thomas speaks simply of cognition through a probable medium, with respect to the force of its probability concerning a given truth—a cognition that can arise through reflection consequent upon demonstrative science—then it is not opinion. St. Thomas seems to have spoken with the same care and qualification in the cited passage from Summa theologiae, I-II. For he says that cognition of a conclusion through a probable medium and through a demonstrative medium differs on the side of the medium according to perfection and imperfection. On the side of the subject, however, opinion, faith, and science differ according to perfection and imperfection; for it belongs to the nature of opinion that one part be accepted with fear of the other opposite. Thus, in the first place he does not name opinion, but in the second he does.

From this it appears that, according to St. Thomas, opinion in its formal character and exercise cannot remain with science, since they conflict on the side of the subject. A probable medium can nevertheless remain along with a demonstrative medium—not insofar as it constitutes and exercises an act of opinion in the intellect, but because cognition of the probable medium remains, as it were, reflectively. A person with science better knows the probative force of probable signs concerning a conclusion, but is not led by those signs, in their actual exercise, to assent. This is what St. Thomas expresses in the cited passage from the third part, saying “that dialectical cognition remains consequent upon demonstrative science, because one who knows the cause can also better know the probable signs from which a dialectical syllogism proceeds.” Therefore, according to St. Thomas, a probable medium remains with a demonstrative one only insofar as the probable signs are better known through scientific cognition. This happens only because the probability of those signs is more deeply understood, which is a kind of reflective cognition of the probable medium itself. Thus it does not constitute an act of opinion in its exercise concerning the truth and object of scientific assent⁴, but rather, in a signified act, the probability of the signs is demonstrated.

It is no objection that, on this account, one could also say that faith and science can coexist in the same subject, which St. Thomas denies. The inference is clear, because through science someone can better know, in a signified act, the authority of a speaker as a reason for believing. Therefore that interpretation is insufficient. I reply: I deny the antecedent. From something demonstrated through a probative medium it does not follow that someone thereby better knows the speaker's authority as a motive, since authority is not manifested through a probative medium; it lacks proof and reasoning, and is reached by simple intuition, while the motive of authority can increase through an act of the will. Opinion, however, or a probable medium, also proceeds in a probative way; therefore its probability becomes better known when aided by the higher probative light of science.

THE BASIS OF THIS CONCLUSION is taken from the very opposition between evidence and nonevidence, certainty and uncertainty, concerning the same truth. To discern and understand this opposition, consider that there is no difficulty in evidence and nonevidence producing incompatible effects in the intellect itself if they affect it absolutely, because evidence and nonevidence in themselves express a privative opposition.

The difficulty is how this opposition is found when the effects arise through different media. It is not incompatible for the intellect to see through one medium and not see through another; thus, when using different media, seeing and not seeing are not contradictory, just as knowing more or less perfectly through different sciences of greater or lesser perfection is not contradictory.

There is, however, a great equivocation here, because different media can coexist in the same subject with respect to the same truth only when the media are not opposed to one another and do not produce opposed effects, or when they are referred back to the objects themselves so as to constitute a different truth or object. But if different media are opposed in such a way that they produce opposed effects—namely, assents, one evident and the other nonevident—and thus affect the intellect concerning the same truth, then they are incompatible even if they proceed from different media. It is like darkness and light: although they are caused by different causes, if they are placed in the same subject they are privatively opposed.

Therefore, when an evident and an nonevident medium, a certain and an uncertain one, concur—and they are such that one lacks in itself a perfection that the other includes—to see whether they also exercise opposition on the side of the subject, we must attend to the effects they leave in the subject. They can be compared with the subject in only two ways. In one way, they affect the intellect absolutely and in their exercise, leaving it at once seeing and not seeing, or failing to reach vision of, one truth; at rest and convinced of the truth and not at rest or fully convinced of that same truth, even though these different motions and affections arise from different principles or motives. In the other way, they do not affect it absolutely and in their exercise in this manner, but with a certain reflection and connotation: for example, judging that something is nonevident and uncertain insofar as it is subject to such nonevident and uncertain premises, but certain and evident insofar as it is subject to other premises. Here being subject to such premises is not only an operative and effective motive leading the intellect to see or not see; it is also an object about which judgment is made as to whether it entails vision or does not entail vision.

In the first way, there must be opposition and conflict between these assents and between the media themselves. Thus St. Thomas, in Posterior Analytics, lecture 44,⁵ teaches from Aristotle that science and opinion conflict in the same way as true and false opinion, which are certainly opposed concerning the same object. The reason is that they produce wholly opposed effects and contrary motions in the same intellect. Through one motion the intellect comes to see clearly; through the other it remains without evidence and does not come to see one and the same truth. Through one it fully rests and its assent is brought to an end; through the other it is not convinced, does not rest, and its indifference is not overcome. Thus to affect a power in this way is to posit incompatible effects in it on the part of the power itself: being moved and not moved, or resting, seeing and not seeing the same thing in act. This is like leading the same eye to see a thing clearly and not see that same thing clearly. Although this occurs through different causes and media, the effects themselves are incompatible and therefore cannot be posited together in the same subject. Generally speaking, all incompatible effects tend to arise from different causes and under different motives, yet they cannot be united in the same subject, because the efficacy of different causes does not remove the formal incompatibility of their effects. So here, if different motives and media function as causes that effectively produce incompatible effects—seeing a thing and remaining obscure without evidence—their incompatibility is not removed by their being introduced through different media or causes.

If it happens in the second way, it is clear that opinion and science are not incompatible, because then it is not opinion but certainty, and the judgment concerns not the same truth but a different one. For the judgment that some conclusion, insofar as inferred from probable premises, is nonevident and uncertain is itself entirely certain: it is not made about the truth inferred, but about its inference and dependence on the premises, and it is certain that this inference is uncertain. In this way, as we said above from St. Thomas, a probable medium can coexist with science as its consequence, because from the cause that demonstrates, one can know the probable signs themselves more perfectly. But we are not speaking here in this sense; we speak of opinion and science insofar as they exercise their effects on the intellect concerning the same truth of the conclusion, not insofar as one is judged in a signified act to be uncertain and the other certain.

That there is opposition between opinion or faith and the evidence of vision, and also the evidence of science, even abstractive science, as St. Thomas teaches in Summa theologiae, II-II, q. 1, a. 5, is clear from this: all scientific evidence, even abstractive evidence, originates in some intuitive vision and is necessarily connected to it, as we saw in the preceding article when St. Thomas enumerated all the modes of evidence. Since scientific evidence is intrinsically connected with and originates from the vision of principles, obscurity, which is immediately opposed to science, is mediately and through a necessary connection opposed to vision. The opposition by which one thing opposes and destroys another also destroys what is necessarily joined to it, just as what is opposed to risible is opposed to rational.

As for the second comparison, between the habit of opinion and the habit of science, many think that these habits are not opposed to one another, but can coexist in the same subject; for they do not involve actual obscurity and evidence, but only an inclination toward formally obscure or evident acts.

NEVERTHELESS, I MUST SAY SECOND: These habits are contrarily opposed to one another as opposed inclinations toward opposed acts, just as in natural things heaviness and lightness are opposed, inclining toward opposed motions, and as virtues and vices are opposed in moral matters.

Thus, when St. Thomas, in the place cited above from Posterior Analytics, lecture 44,⁶ had said, following Aristotle, that opinion and science are opposed like true and false opinion, he speaks in the same terms of opinion as a habit and of the other habits that are always directed toward truth, with which he compares science, as is clear there in the paragraph “He compares science with certain habits.”⁷ Therefore, when he posits contrariety between them, he is speaking not only of opinion as an act, but also as a habit. He speaks in the same way of the habit of opinion and of science in Posterior Analytics, book 2, lecture 20, at the end.⁸

The REASON is taken from what was said: it is impossible for some acts to be opposed to one another while the habits inclining toward those acts are not opposed, since inclinations are called opposed precisely insofar as they incline toward opposed motions. Therefore, wherever the opposed motions or acts themselves are found, the inclinations must also be opposed. Opposed inclinations are contrary to one another, as is clear in the examples given. Therefore they cannot coexist in the same subject in the way contrary forms cannot coexist.

It should be noted, however, that contrary forms expel one another from a subject when they are perfect, not when they are in an imperfect and weakened state. A contrary form, if in a perfect state, perfectly subjects the subject's indifference to itself and reduces it to uniformity with itself, and so does not allow indifference toward the contrary opposite to remain. Therefore the evident habit must inform the subject perfectly in order to expel the obscure one. This is why the light of glory, unless given in a perfect state, does not expel the habit of faith, since it is not given in the mode of a habit, but in a transient manner. Thus St. Thomas teaches in Summa theologiae, II-II, q. 175, a. 3, ad 3, that the light of glory given to Paul when he saw the divine essence in rapture did not remove the habit of faith, because it was not given in the mode of a habit. Likewise, if some demonstration were given in so imperfect a way that it did not generate a habit, as with that vision of glory, or if it were not given permanently but transiently, it would not remove the habit of opinion. But if the demonstration is true and perfect, so that it is clearly and manifestly connected with a self-evident proposition, a single act fully convinces the intellect and establishes it in the inferred truth, as St. Thomas says in Summa theologiae, I-II, q. 51, a. 3. Therefore the habit of science by its nature always expels the habit of opinion, because it is always a perfect habit and thus is like an intense contrary form that always expels its opposite.

As for the third comparison, between a habit and an evident or nonevident act, I SAY FINALLY: By their nature they are not formally opposed, but can coexist in the same subject; nevertheless, they can expel one another when an act generates a perfect habit, which, precisely because it is perfect, expels the opposite from the subject.

THE FIRST PART of the conclusion is proved because there is no formal opposition between a habit and an act, but an effective or dispositional one, insofar as an act disposes toward the opposite habit, or insofar as a habit produces an act formally opposed to another act. Act and habit are not opposed to each other: a habit signifies only an inclination toward something, whereas an act signifies an actual tendency. A tendency toward the opposite can nevertheless coexist with an inclination toward one thing. Thus a stone can tend upward through a violent impulse while its heaviness, which inclines it toward the center, remains; a person with the habit of virtue can actually sin; and a person with the habit of faith can actually see God in a transient manner, as St. Thomas expressly teaches in Summa theologiae, II-II, q. 175, a. 3, ad 3. Therefore, in the same way, someone with the habit of science can elicit an act of opinion and yet not lose his science.

ON THE CONTRARY, someone who has the habit of opinion, if he elicits a demonstrative act, by that single act generates a perfect habit of science, because it perfectly convinces the intellect and overcomes all its resistance. Such a habit cannot coexist with the habit of opinion because it fully convinces, just as one perfect contrary form expels another. But this occurs through the perfect habit generated by that act, not merely through the act's formal character in relation to the opposite habit.

If infused habits, such as grace and charity, are expelled by a single act opposed to sin, as St. Thomas teaches in Summa theologiae, II-II, q. 24, a. 12, this is not because the act formally destroys the opposite habit, but because it impedes the influx of the preserving cause. By sin a person turns away from God and thus places an obstacle to receiving from God the light of grace, by which a person is turned toward God as an end. It is like someone who closes a window and thereby prevents the light of the sun from illuminating the air. Therefore those habits are not destroyed through the formal opposition of an act, but through the opposition of an impediment. This does not apply here, where the habits of science and opinion do not depend for their coming-to-be and preservation on an extrinsic cause whose influx could be impeded by an opposed act.

ARGUMENTS ARE ANSWERED.

First it is argued, because the whole basis of the opposition between an act of science and an act of opinion is either the plurality of acts or contrariety. It is not merely their plurality; otherwise they would be no more incompatible than two acts of science or two acts of opinion, or any other disparate acts. Nor is it contrariety, because this whole contrariety is due to clarity and obscurity, and to certainty and uncertainty. But these are not contrary-incompatible insofar as they are had through different media. The same thing can have different causes, some necessary and some contingent; according to its necessary causes we judge it unable to be otherwise, and according to its contingent causes we judge it able to be otherwise. We affirm without contradiction the proposition “The dead rise” according to supernatural causes and deny it according to natural causes. Therefore, from different causes and motives, we will likewise judge the same conclusion certainly and uncertainly, evidently and nonevidently. Hence St. Thomas, in Summa theologiae, I-II, q. 67, a. 3, posited opposition between opinion and science, or between a probable and demonstrative medium, only with respect to the same act or medium, not with respect to the same subject through different media.

It is confirmed that contrary acts concerning the same object can coexist in the will; therefore acts of opinion and science can also coexist in the intellect.

The consequence is clear, because these acts are not privatively or contradictorily opposed to one another, since each is a positive act; nor are they contradictory on the side of the object, since each affirms the same truth.

The antecedent is proved as follows: Christ's will was simultaneously affected by joy and sadness concerning the same object, namely his own passion, which grieved him as a natural evil and gladdened him as the redemption of humankind.

I ANSWER that the opposition between an act of opinion and an act of science is due to contrariety, not just any contrariety, but one that entails privatively opposed effects: seeing and not clearly seeing the same object, and being certain of it by judging that it cannot be otherwise, or not being certain by judging the opposite. St. Thomas, in the passage cited above, equates this opposition with the opposition between true and false.

As for what is said about different media, we reply that assents given through different causes and media, necessary and contingent, as the formal reasons of opposed judgments, are opposed in themselves. They are not opposed if the causes and media themselves are considered reflectively and in a signified act as objects about which a judgment of probable opinion or necessity is made; for then the judgment is not about the same object. Likewise, in the proposition “The dead rise” and “The dead do not rise,” if both are taken absolutely, they contradict and conflict in the intellect. But if they are not taken absolutely and one explains something the other does not—that is, “The dead rise according to God's power, but do not rise according to natural causes”—then they do not concern the same thing and consequently do not contradict one another. Opinion and science likewise, when exercised absolutely, produce opposed effects. But if they are considered in a signified act and a judgment is formed not merely about the things themselves, but about the certainty or uncertainty they have insofar as they depend on such causes and media, then they do not contradict one another, and the judgment is not made in an act of opinion but with certainty. In sum, opinion and science are opposed like true and false opinion, as Aristotle says in ch. 26 of Posterior Analytics, book 1⁹, and St. Thomas in lecture 44.¹⁰ Therefore, just as we speak of judgments opposed in truth and falsity, so we must speak of an opining and a scientific judgment. In Summa theologiae, I-II, q. 67, a. 3, St. Thomas posited opposition between science and opinion not only on the side of the medium or act, but also on the side of the subject, as he expressly says there and as we explained in the preceding article.

In reply to the confirmation, we say that contrary motions of joy and sadness in the will do not concern the same object according to the same account of good and evil, but according to different accounts. Christ the Lord rejoiced in his passion insofar as it was for the salvation of humankind, but grieved over it insofar as it was a natural evil. These are formally different objects, even though materially they are the same.

If you press the point: Why could opinion and science likewise not concern the same material object, if they concern it under different considerations? I reply that if the formal aspects of opinion and science produced different truths by constituting different objects, the same account would apply as in the case of the motions of the will.

In the intellect, however, the fact that one truth is inferred with respect to an evident medium or with respect to a nonevident one does not change its character as an objective truth. If the same truth remains, but its illumination comes from different media, one of which illuminates it fully and the other obscurely, they thereby produce opposed effects in the intellect concerning the same truth, as the matter illuminated by these two opposed lights, even though the lights belong to different habits; they always produce opposed effects.

But the object of the will, which is the good, changes in its very character as good through a different relation and reference alone. The same thing, compared with one thing, is good and suitable, and compared with another is unsuitable, because good and evil are taken relationally. Thus a different object is constituted in the character of good and suitable. Different motions therefore become nonopposed precisely because their objects change. Yet even in the sensitive appetite, different motions of joy and sadness cannot occur concerning different objects, because they involve bodily motions of expansion and contraction around the heart, which are absolutely incompatible at once because they occur in different positions.

Second it is argued: Divine faith is obscure and does not conflict with natural science, which is evident; therefore not every obscurity conflicts with evidence.

The antecedent is proved first: faith and vision conflict insofar as vision is related to the intellect's rest, whereas believing is like motion. But divine faith is only a motion tending toward the vision of glory, not toward natural science; therefore it does not conflict with natural science, but with the vision of glory. Second, faith remains in a Christian philosopher concerning the proposition “God exists”; otherwise he would hold it with less certainty than a faithful layman who believes it, and so would be worse off. Third, Paul had faith together with the vision of glory in his rapture, as St. Thomas says in Summa theologiae, II-II, q. 175, a. 3, ad 3; therefore faith does not conflict with an act of vision or science. Finally, according to the opinion that one body can be placed in two locations, if a person is placed in Rome and in Complutum, he will see the Pope in Rome and believe what is said about him in Complutum. Therefore clear and obscure vision will not be incompatible in the same subject concerning the same thing.

I ANSWER by denying the antecedent, which is the express position of St. Thomas in Summa theologiae, II-II, q. 1, a. 5. The opposition between obscurity and the evidence of vision is the same as that between obscurity and the evidence of science, which is intrinsically connected with and necessarily derived from the vision of principles.

To the first proof, we reply that divine faith is related to vision as motion to rest in two ways. In one way, with respect to the character of an end and perfect enjoyment; in this way its end and rest is only the vision of glory. Second, with respect to the manner of proceeding, though not with respect to the fullness of enjoyment; in this way the evident manner of proceeding in natural science also terminates the manner of proceeding in faith, because through faith the intellect is taken captive by obscurity and, as it were, placed under another's terms, whereas through science it is evidently convinced by its proper object.

To the second proof: theologians have a long dispute about how faith remains in a Christian philosopher, which we cannot resolve here. Briefly, however, we say first that faith can remain in a Christian philosopher concerning the proposition “God exists” with respect to readiness of mind. Thus he is not worse off with respect to merit and habitual certainty, even if he is so with respect to actual certainty.

Second, faith remains concerning the proposition “God exists” by believing that God exists as a supernatural author, in which way he must be known by one who is justified. For in the article “God exists and is a rewarder” all the other supernatural articles are implicitly contained, as St. Thomas teaches in Summa theologiae, II-II, q. 1, a. 8. Supernatural truths cannot be contained in the truth “God exists” insofar as it is precisely a natural truth. Hence St. Thomas, On Truth, q. 14, a. 9, ad 8,¹¹ says “that God's existence, insofar as it is demonstrated, is not an article of faith, but the unity of the divine essence, as it is held by the faithful together with omnipotence, providence over all things, and other such matters that cannot be proved.” He teaches the same in Summa theologiae, II-II, q. 1, a. 8, ad 1. But science, not faith, remains concerning the proposition “God exists as a natural author and as knowable evidently from natural effects.” Taken in this way, however, it is a formally distinct truth and a distinct proposition from the first, which reaches God's existence according to truths supernaturally revealed.

Or, finally, third, we say that concerning the proposition “God exists,” even insofar as God is a natural author, a Christian philosopher has greater actual certainty than a faithful layman, which is shared from faith through its connection with that proposition. Faith leaves behind a certain judgment that the things of faith are more certain than every natural cognition; in this judgment the intellect apprehends certainty, not the obscurity of faith. This judgment strengthens the intellect as it demonstrates, so that it is certain of its demonstration and of the truth “God exists,” and does not suppose that it is false or that the demonstration is fallacious. In other natural demonstrations, however, because of the weakness of our reason, one can fear this, since errors are often mixed into them; faith serves to correct these, as St. Thomas teaches in Against the Gentiles, book 1, ch. 4, and Summa theologiae, II-II, q. 2, a. 4. Thus the demonstration itself is strengthened in this way and shares certainty from faith, by forming that judgment without receiving obscurity from faith in that judgment. In apprehension, however, we can receive a judgment about certainty without apprehending what concerns obscurity; thus, through such a distinction, faith influences the demonstration with certainty through that judgment, not with obscurity.

To the third proof, we reply that the act of vision in Paul did not exclude the habit of faith, because that act of vision was without a habit, since it did not have a permanent state. Rather, it was elicited by a help—that is, by a transient quality supplying the place of a habit—and so the habit of faith was not excluded.

In reply to the confirmation, we say that, granting the case of a body being placed in two locations (which we shall nevertheless reject in Physics, book 4¹²), one must say either that the vision and nonvision do not conflict because they concern different locations, in which the person functions, as it were, as two persons and subjects; or that he would see in one location everything he saw in the other, because the seeing eye is identical, and he would be in each location as if, while existing in one, he saw so perceptively as to reach things in the distant location, since he reaches both locations while existing in either.

Finally it is argued: Someone who has the habit of science can use a probable medium to prove a conclusion already demonstrated; for it often happens that probable media and arguments are accumulated to prove the same thing, some probable and others demonstrative. Then these probable arguments generate some habit, since repeated acts generate a habit, and it is not a scientific habit, as is clear in itself; therefore it is an opinion-forming habit. Therefore these habits can coexist.

I ANSWER that if someone with the habit of science elicits an act of opinion by exercising the very fear and assent of opinion, and not merely by knowing the force of probable signs more perfectly (as St. Thomas says can happen in someone who uses a probable medium after a demonstration), that opinion-forming assent will not generate a habit because of an impediment in the subject, in which the habit of science is present. This habit actualizes the subject firmly and perfectly and does not allow an opposite habit to coexist. Here it differs from the habit of virtue and vice: virtue is generated not by a single act but by habit and practice, because a single act does not overcome the whole indifference of reason toward the good, owing to contingency and freedom toward the good and the many circumstances it requires, as St. Thomas teaches in Summa theologiae, I-II, q. 51, a. 3. Thus it is also not expelled by a single act; rather, several vicious acts can occur, through which the mind becomes accustomed to the opposite of virtue and thereby adheres less firmly to virtue. This leaves room for the opposite habit to be generated gradually. This does not apply to the habit of science in relation to opinion, because it is generated perfectly by a single act and makes the intellect adhere with certainty by the force of evidence, not by the force of habit.